| 摘要 |
PROBLEM TO BE SOLVED: To attain desired characteristics at low cost, without increasing man- hours by implanting B at an ion implanting energy in specified range to change he surface concn. of an epitaxial layer as little as not to invert it. SOLUTION: The specific resistance of an epitaxial layer 15 to 0.5-1.0Ω, an oxide layer 16 is grown for selective diffusion in a thickness range of 300-600nm, the guard ring diffusion for ensuring a breakdown voltage is made by the ion implanting method to form a layer having a reverse conductivity to that of a semiconductor substrate on the guard ring. B is implanted into the other main face of the film 16 in the implanting condition that the implanting energy is 50-150keV and dosage is 5×10<14> -1×10<16> /cm<-1> so that the concn. of B implanted through the film 16 into the skirt has influence on the surface concn. of the layer 15. Thus, desired characteristics can be attained, without increasing man-hours. |
